Panels which will be formed into printed wiring boards are comprised of a dielectric substrate, usually of filled synthetic polymer composition material. The panels have a thin metal foil laminated on one or both sides, which will be etched to form circuit patterns. The circuit patterns are usually small compared to the panel, but for convenience of handling and cost, a plurality of circuit patterns are formed on each panel, commonly called a multi-up panel.
Multi-up patterns are panels where a plurality of circuit patterns are processed together on the same panel. These circuit patterns may be related or unrelated and are not electrically connected to each other. The reason a plurality of circuit patterns is incorporated in one panel is purely from an economic handling viewpoint. If a plurality of circuit patterns can be processed at the same time, the number of handling steps per pattern is reduced. When circuit patterns are small compared to the panel size, the use of a multi-up arrangement is economically successful. Each of the circuit patterns represents a printed wiring board when it is ultimately cut out of the panel.
As the panels are processed, some of the circuit patterns may become defective. Such is particularly true when the circuit pattern is formed with very narrow conductors and spaces. In the past, this has resulted in the rejection of the entire innerlayer panel or the creation of one or more multilayer printed wiring boards on a multi-up panel with an inoperative layer therein. It is particularly difficult to handle the panels between processing steps when the substrate and the copper foil thereon are particularly thin.